This is not a foolish question, it is a brilliant question, but at the same time we must know that there is no human formula to enter the kingdom of heaven, but all this is about grace, an undeserved gift that God gives us through the death of His Son on the cross of Calvary.
But if we talk about entering the kingdom of heaven there is something that is proper to each believer: “Born again”. We can not say that we are Christians if we are not born again, this is the distinguishing mark of each one of us and our beloved Lord Jesus Christ spoke about the new birth:
3 Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother’s womb, and be born?
5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
Nicodemus was a teacher of the law, a man who represented the knowledge of Israel, however, he knew nothing about the new birth. Let’s not fall into the deception of being inside the temple and being part of it and not being a born again creature and that has knowledge of it.
It is true that there are no human formulas to enter the kingdom of heaven, the truth is that if we are really Christians this means that we are born again people who have renounced sin, the world and its desires.
God has given us the new birth through the death of His Son on the cross and thanks to it we are saved and being saved makes us have good works, worthy to show that we are new creatures.